HWComposer: setPowerMode to DOZE even if support is unknown

If a display has not been turned on since boot, we do not know whether
it supports doze. Rather than treating this as not supported, make
Display::supportsDoze return an error if the capabilities have not been
queried yet. If supportsDoze returns this error, try to set the mode to
DOZE(_SUSPEND) anyway. This allows properly waking from AOD.

If the call to Display::setPowerMode fails, this means it truly is not
supported, so fallback to the old behavior of turning it ON.

Fixes: 274722476
Test: manual
Test: GraphicsComposerAidlTest#SetPowerModeUnsupported
Change-Id: Ia88603565713ea4b6ec5142b693d2df1302131ea